Kickboxers, reindeer herders, composers and the inhabitants of a whole suburban street have been recruited – not all of them willingly – to shore up Vladimir Putin's crumbling United Russia party before December's parliamentary elections in Russia.

The All-Russia People's Front, a nationwide coalition of public groups set up by Putin, also embraces trade unions, car-owners' clubs, a beekeepers' association and scores of other organisations. They have all rallied to the prime minister's flag and, this autumn, will help choose candidates for the parliamentary poll, which is a springboard to the presidential election in March next year.

Putin has not said he will run for the presidency, but warned on Thursday that the campaign would be so dirty he would need to "wash, in the hygienic sense of the word but also in the political sense" as soon it was finished. "After all the campaigns which we shall have to endure, you have to be properly hygienic. Unfortunately, this is an inevitable process," he said.

Putin is still the frontrunner to be the ruling elite's candidate, in front of the incumbent, Dmitry Medvedev. However, beyond the usual effusive coverage on state TV, his latest political gambit is coming under increasing criticism. The People's Front was ridiculed on blogs and in liberal media after it emerged that members of several of the organisations that signed up had not approved their entry; on the contrary, they were livid at being portrayed as supporters.

Mikhail Arkadyev, 53, a member of the Russian Union of Composers, wrote a withering open letter of protest to its leadership after learning from news reports that the union had joined the "odious and baneful" front without consulting him or others. "Not only does this violate my individual rights and elementary democratic procedures," he wrote, "but I do not in principle accept the political programme and social role [of the front] created by Putin exclusively for the simulation and profanation of the democratic process in Russia.

In an interview with the Guardian, Arkadyev said: "It is under Putin's leadership that the criminal world and state structures in our country have completely melded. I do not support him and have no intention of giving this system legitimacy by voting in sham elections."

Another musician, Lyudmila Korabelnikova, wrote: "I still can't believe that the union, at the foundation of which lies a concept of inviolability of creative individuality, joined us en masse to the prime minister's front without asking every one of us."

She asked not to be included because "to no degree do I sympathise with the ideology or the work of this front, which I consider fatal for Russia".

The complaints came just a couple of days after a plenary session of the Russian Union of Architects voted to overturn its entry into the coalition, following a campaign by one vocal member, Yevgeny Ass. "Joining one or another political organisation is the personal choice of each individual architect, as a citizen rather than a professional," wrote Ass.

Speaking on Thursday at a United Russia conference in Yekaterinburg, a city in the Urals, Putin tried to dampen the discontent over coerced support of his movement. "We are against people joining the front on somebody's order … or that large-scale involvement and participation are artificially drummed up," he said. The decision to join should be expressed by people themselves "in the places where they live", he said.

That promise rang hollow as several large organisations and unions – including the Russian Railway Workers Union – joined without balloting their members. By contrast, the inhabitants of Sovkhoznaya [Collective Farm] Street in Vladimir, a historic town near Moscow, did take a vote but have yet to be officially registered in the front.

Political analyst Alexei Mukhin said Putin's overriding urge was to use the People's Front to garner nationwide legitimacy as support for United Russia slips – it dipped below 40% in some areas for the first time in regional elections in March.

"The fact that some members of these big organisations won't agree with being in the front is neither here nor there," said Mukhin. "Their bosses will tell them what to do and they will obey."

• This article was amended on 4 July 2011. In the original we said the musician Mikhail Arkadyev was 58. This has been corrected.